Beat the boss! Use the arrows to move. Press "z" to jump. Holding "z" lets you jump higher. Press "x" to attack. hitting an attack bumps you backward. Press "c" to dash. Dashing is only possible once if you are in the air. Press "a" to heal. If you need to cancel the heal, press "s".
This game is still unfinished, as evidenced by the graphics and lack of sound/UI.